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RECHARGING DEVICE FOR PELLET IMPACT DRILL BITS 2 Sheets-Sheet 1 Filed Nov. 18, 1952 P za-i JOF'IQEiOPC LO SS {Saver-icon fi ululjw Utter-0.61.5

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@g Q 30 C) WIS John Ortlojj WWWWW RECHARGING DEVICE FOR PELLET IMPACT DRILL BITS John E. Ortlotf, Tulsa, Okla., assignor to Esso Research and Engineering Company, a corporation of Delaware Application November 18, 1952, Serial No. 321,176

3 Claims. (Cl. 255-61) The present invention is concerned with a novel method and apparatus for the drilling of bore holes into the earths substrata, employing what may be termed pellet impact drilling. The drilling method of the present invention employs novel principles to secure the recirculation and replenishment of solid pellets utilized in a bore hole for effectively drilling the hole. The force of the pellets impinging on the bottom of the hole pulverizes the formation and materially aids in the drilling of the hole. Circulation of the pellets is maintained by a bit arrangement involving the propulsion and recirculation of pellets in a fluid stream. The particular adaptation of the present invention is to provide a novel and effective procedure for the replenishment of the pellets at the bottom of the bore hole.

The basic principles of the pellet impact technique for the drilling of bore holes in the earth involves the use of a stream of fluid pumped from the surface of the earth through a tubular member to a jet nozzle adapted to provide a high velocity jet of fluid directed downwardly toward the bottom of the bore hole. Means are provided to entrain in the high velocity fluid jet a multitude of hard, dense pellets which are accelerated to high velocity in the jet stream and thereby acquire considerable kinetic energy so that when the pellets impinge against the formation the resulting impact and fracturing forces exert a drilling action. Means are also provided for separating pellets from the up-flowing returning stream of fluid and reintroducing the pellets into the jet stream. Preferably the pellets that are employed are smooth, nonabrasive, essentially spherical, and of substantial size, in the range of about one-eighth inch to about one inch in diameter. The basic principles of the technique of drilling by pellet impact are set forth in co-pending application Serial No. 268,873, filed by P. S. Williams on January 29, 1952, and entitled Pellet Impact Method and Apparatus.

While this procedure is very effective and holds promise, one problem encountered is the replacement of the pel lets in the bottom of the bore hole. This is due to the fact that the so-called primary nozzle which is used to secure the necessary velocity usually has an interior diameter less than the diameter of the pellets. It thus follows that it is not possible to pump the pellets down the drill string wih the mud. Suggestions have been made that the pellets be supplied to the bottom of the bore hole by allowing them to fall by gravity against the up-flowing mud in the peripheral area between the bore hole and the drill string. This is not very practical since a large loss of pellets occurs due to these pellets being caught along the inner surface of the bore hole.

In accordance with the present invention a particular adaptation of apparatus is employed in conjunction with the impact pellet drilling bit which permits the pellets to be passed downwardly within the drill string and to be released when desired into the area between the drill string and the bore hole.

The present invention may be more fully understood it States Patent ice by reference to the drawing illustrating embodiments of the same.

Figure 1 illustrates a typical pellet impact drilling apparatus while Figure 2 illustrates the apparatus of the present invention which is positioned directly above the portion of drill stem 11 shown in Figure 1. Figure 3 illustrates the apparatus of Figure 2 wherein the port is opened so as to permit pellets to flow from within the drill string to the area without the drill string, thus bypassing the primary nozzle.

Referring specifically to Figure 1, the impact drilling apparatus of this invention is illustrated in drilling position adjacent the bottom of a bore hole 1 which has been drilled by the apparatus. The drill is suspended on a tubular pipe 11 which may be of the nature conventionally used in rotary drilling operations. The drill illustrated in Figure l essentially comprises two elements. An inner nozzle element 3 is provided which may be a continuation of the drill pipe 11 or alternatively may be the continuation of a tubular member 2, of smaller diameter than the drill pipe, joined to the drill pipe by a reducing nozzle 12. Nozzle element 3 terminates at its lower end in a jet nozzle 4. The jet nozzle assembly is therefore of a character to result in the propulsion of a fluid jet at its lower end when drilling fluid is pumped through the drill pipe at a satisfactory flow rate. The single fluid jet provided in this apparatus is directed vertically downward along the central axis of the bore hole.

Encircling the inner nozzle element 3 is a sleeve 5. This sleeve is formed and positioned so as to extend upwardly from a level below the termination of the jet nozzle 4 to a level above the jet nozzle. As illustrated, the sleeve has an external diameter substantially greater than the diameter of the drill pipe 11. This configuration is employed to provide an annular channel encircling the jet nozzle assembly having a substantially smaller crosssectional area than provided above the sleeve. The upper termination of the inner portion of the sleeve may be flared upwardly and outwardly, as shown, so as to provide a hopper for the collection of pellets settling from the fluid above the sleeve.

Suitable structural members such as webs, or the like, may be employed to connect the sleeve 5 in fixed relation to the nozzle element 3. To minimize problems of wear caused by impingement of the circulated pellets through the annular channel between sleeve 5 and nozzle 3, it is desirable to employ longitudinal ribs which extend vertically through this annular channel. Ribs of this character are identified by numeral 8, extending from the upper termination of sleeve 5 to a point adjacent and above the jet nozzle 4-. The vertically positioned ribs 8 are thus only exposed to direct impingement of the pellets on the upper downwardly sloping edge 10 of each rib where the pellets have a relatively low velocity. The apparatus is provided with blunt stand-off rods or plates 20 which permit the apparatus to rest on the bottom of the bore hole while positioning the nozzles at a fixed distance from the bottom of the bore hole.

The operation of the drill of Figure 1 may now be appreciated. Assuming that a drill hole hasbeen initiated in the earth for at least a short distance, the apparatus of this invention may be placed in operation by lowering the drill to a position spaced from the bottom of the hole in the manner shown. Drilling mud or any other desired fluid is then pumped through the drill pipe so as to be ejected from the jet nozzle 4 in the form of a high velocity constricted jet. This fluid jet passes through the elongated constricted passage 9 provided in sleeve 5 and impinges on the bottom of the bore hole. The fluid will then flow outwardly and upwardly into the bore hole so as to be returned to the surface of the earth for recirculation through the drill pipe and through the jet. A multidropped into the annular space between the bore hole'and drill pipe at the surface of the earth or alternatively in the bore hole annulus adjacent the drilling apparatus of Figure 1 by means of the apparatus of-Figures 2 and 3, which will be subsequently described. These pellets will drop downwardly and will enter sleeve 5 so as to be entrained in the fluid jet from nozzle 4. Traveling with the energy provided by the jet of drilling fluid, the pellets will be forcefully directed against the bottom of the bore hole. The velocity of the drilling fluid will then carry the pellets outwardly and upwardly along the bottom and wall of the bore hole to a point somewhat above the upper termination of the sleeve 5. This movement of the pellets will occur by virtue of the fact that the sleeve 5 has a diameter which fills the major portion of the crosssectional diameter of the bore hole. Consequently, a relatively confined annular channel is provided for the drilling mud between the sleeve 5' and the bore hole 1.

The drilling mud will thus travel upwardly adjacent the sleeve at a relatively high linear velocity, serving to maintain entrainment of the pellets. However, above the upper termination of the sleeve 5 a substantially greater cross-sectional flow area is provided for the drilling mud. Consequently, the linear velocity of the drilling mud will drop sharply somewhat above the upper edge of the sleeve. This action will slow the drilling mud sufficiently to permit separation of pellets. These pellets will therefore settle out of the mud stream, dropping into the outwardly flared termination of the sleeve 5. Under the force of gravity, and in part due to the aspirating effect of the jet from nozzle 4, the pellets will drop downwardly in the annular space between the nozzle element 3 and the sleeve 5 to be caught by the jet of drilling mud and again impinged against the bottom of the bore hole.

it will be noted that the sleeve 5 extends below the nozzle 4 to provide an elongated passage or nozzle 9 having a greater diameter than that of nozzle 4. Nozzle 4 may be referred to as a primary nozzle while nozzle 9, provided by sleeve 5, may be referred to as a secondary nozzle. The function of the primary nozzle, as described, is to convert a substantial portion of the pumping pressure applied to the drilling fluid to velocity energy. The primary nozzle thus serves to provide a high velocity, constricted and directed, fluid jet. The secondary nozzle concentric with, but below, the primary nozzle serves as a mixing chamber to entrain pellets in the fluid jet and to accelerate and direct the jetted pellets. The secondary nozzle must have a greater diameter than the primary nozzel to achieve this eflect since a greater volume of material (fluid plus pellets) must flow through the secondary nozzle. Again the greater diameter of the secondary nozzle provides an aspiratory effect contributing to the eifective entrainment of the pellets in the fluid jet.

In general the diameter of primary nozzle 4 will vary from about 0.1 to 1 inch and is preferably in the range of about 0.5 to 0.8 inch. The diameter of the secondary nozzle should preferably not exceed about 5 inches but the ratio of the secondary to the primary nozzle should be in the range from about 3 to 7 diameters per one diameter of the primary nozzle. A preferred ratio is to have the secondary nozzle about 4 to 5 diameters as compared to one for the primary nozzle. On the other hand the pellets should have diameters from about A to /2 of the diameter size of the secondary nozzle. A preferred diameter of the pellet is about /3 of the diameter of the secondary nozzle, however in all instances the diameter of the pellets is greater than the diameter of the primary nozzle. As pointed out heretofore under these conditions it is not possible to eflectively and efficiently replenish pellets in the bottom of the bore hole by dropping them down through the drill pipe.

Referring to Figure 2 the apparatus of the present invention is illustrated. The apparatus consists of a cylindrical member 22 the inner bore of which slidably receives a second cylindricalmember 21 which may be termed a piston element. Upward motion of piston 21 is limited by engagement of tapered shoulders 25 and 26 and downward motion of the piston is limited by cngage ment of shoulder 27 with shoulder 28. Member 21 has a central bore 18 which is closed 011 at its upper end by a head 24 provided with a plurality of fluid ports 15 having a diameter less than that of the pellets that are chosen for use with the apparatus. A pellet escape port 17 in the wall of member 22 is closed 011 when piston 21 is in the position shown in Figure 2 but is open when piston 21 is in the position shown in Figure 3. Preferably piston head24 slopes in the direction of port 17 to ensure complete removal of pellets from chamber 14 when the port is opened. Proper alignment of the piston and cylinder is maintained by means of a key or spline 30. This apparatus is positioned immediately above the apparatus of Figure 1 in drill string 11 by means of suitable tool joints 13 and 23.

In operation the drilling fluid and the pellets flow downwardly within the drill stem into the area 14. The fluid passes through ports 15 into passageway 13 and from thence througha lower portion of the drill string 11 into nozzle element 3 as previously described. The ports are too small to permit the passage of pellets which accumulate in area 14. Suitable seals 16 are provided so as to seal the drilling fluid from passing into pellet escape port 17. A shear pin 19 is also illustrated. This shear pin may be used if it is desired to transport a charge of pellets to thebottom of the hole with the bit. When the apparatus is used for this purpose, after the bit reaches bottom the drill stem can be raised a short distance off bottom and circulation started. Fluid circulation causes the pellets to close the fluid circulation ports 15, building up pressure in the drill pipe sufliciently to shear the pin. This forces piston 21 down to the position illustrated in Figure 3 wherein port 17 communicates with the area 14 thus permitting the pellets to flow from within the pipe string to the annulus between the bore hole and the pipe string. After the pellets have been discharged into the outer annulus the drill string is lowered to the bottom of the bore hole and supported by positioning means 20 thus causing piston element 21 to move upwardly within cylindrical element 22 thereby closing port 17.

If it is desired to recharge the apparatus with pellets after it has been in operation for a period of time, it is merely necessary to raise the drill string a suflicient distance to ensure that the apparatus will clear the bottom of the bore hole even with the piston 21 in its downward position, insert the desired charge of pellets into the top of the drill string, and pump pellets and fluid down through the drill string. Piston 21 will move down to the position of Figure 3 either by its own weight plus the weight of the apparatus supported therefrom or by the action of these combined weights plus the pressure of the fluid being circulated through the drill string. After suflicient time has been allotted to ensure that the pellets have passed out through port 17, drilling may be resumed by lowering the drill string sufliciently to move piston 21 upwardly to close port 17.

The present invention is primarily concerned with an improvement in impact drilling procedure. The invention is particularly directed toward the replenishment of necessary pellets in an impact drilling apparatus wherein it is desirable that the diameter of the pellets exceed the diameter of the primary nozzle.

Having described the invention, it is claimed:

1. In a drill bit assembly for drilling a bore hole in the earth by entraining pellets in a high velocity stream of fluid, which assembly includes a tubular support member terminating in a jet nozzle adapted to produce said high velocity fluid stream, said nozzle being of smaller diameter than said pellets, an improved apparatus for supporting said assembly from a drill pipe in the bore hole and for introducing pellets from said drill pipe into said bore hole in the vicinity of said nozzle which comprises a cylindrical member attachable to a drill pipe, said member having a vertical bore extending therethrough and a side port communicating with said bore, a piston member slidably fitting within said vertical bore in said cylndrical member and slidable from a first position closing said port to a second position exposing said port, said piston member having a vertical bore extending therethrough, a head member at the top of said piston closing the bore thereof, said head having at least one port communicating with said last named bore, said port being of smaller diameter than said pellets, and means for supporting said first named tubular support member from said piston member, whereby when said assembly is above the bottom of the bore hole said piston will move to said second position and when said assembly is lowered into contact with the bottom of the bore hole said piston will be moved to said first position.

G 2. Apparatus as defined by claim 1 when the upper surface of said head member slopes downwardly in the direction of said side port in said cylindrical member. 3. Apparatus as defined by claim 1 including a shear pin initially holding said piston member in said first position within said cylindrical member.

References Cited in the file of this patent UNITED STATES PATENTS 814,427 Brooks Mar. 6, 1906 902,564 Davis Nov. 3, 1908 1,502,851 Gale July 29, 1924 2,233,260 Hawthorne Feb. 25, 1941 2,307,658 Appleby Jan. 5, 1943 2,329,393 Davis Sept. 14-, 1943 

1. IN A DRILL BIT ASSEMBLY FOR DRILLING A BORE HOLE IN THE EARTH BY ENTRAINING PELLETS IN A HIGH VELOCITY STREAM OF FLUID, WHICH ASSEMBLY INCLUDES A TUBULAR SUPPORT MEMBER TERMINATING IN A JET NOZZLE ADAPTED TO PRODUCE SAID HIGH VELOCITY FLUID STREAM, SAID NOZZLE BEING OF SMALLER DIAMETER THAN SAID PELLETS, AN IMPROVED APPARATUS FOR SUPPORTING SAID ASSEMBLY FROM A DRILL PIPE IN THE BORE HOLE AND FOR INTRODUCING PELLETS FROM SAID DRILL PIPE INTO SAID BORE HOLE IN THE VICINITY OF SAID NOZZLE WHICH COMPRISES A CYLINDRICAL MEMBER ATTACHABLE TO A DRILL PIPE, SAID MEMBER HAVING A VERTICAL BORE EXTENDING THERETHROUGH AND A SIDE PORT COMMUNICATING WITH SAID BORE, A PISTON MEMBER SLIDABLY FITTING WITHIN SAID VERTICAL BORE IN SAID CYLINDRICAL MEMBER AND SLIDABLE FROM A FIRST POSITION CLOSING SAID PORT TO A SECOND POSITION EXPOSING SAID PORT, SAID PISTON MEMBER HAVING A VERTICAL BORE EXTENDING THERETHROUGH, A HEAD MEMBER AT THE TOP OF SAID PISTON CLOSING THE BORE THEREOF, SAID HEAD HAVING AT LEAST ONE PORT COMMUNICATING WITH SAID LAST NAMED BORE, SAID PORT BEING OF SMALLER DIAMETER THAN SAID PELLETS, AND MEANS FOR SUPPORTING SAID FIRST NAMED TUBULAR SUPPORT MEMBER FROM SAID PISTON MEMBER, WHEREBY WHEN SAID ASSEMBLY IS ABOVE THE BOTTOM OF THE BORE HOLE SAID PISTON WILL MOVE TO PAID SECOND POSITION AND WHEN SAID ASSEMBLY IS LOWERED INTO CONTACT WITH THE BOTTOM OF THE BORE HOLE SAID PISTON WILL BE MOVED TO SAID FIRST POSITION. 